Induction system for a two-cycle engine of three cylinders



March 10, 1953 E. c. KLEKHAEF-ER 2,630,791

INDUCTION SYSTEM FOR A TWO-CYCLE ENGINE- OF THREE CYLINDERS Filed May24, 1951 26 Ag I INVENTOR."

A [Zner fia r fllorneys Patented Mar. 10, 1953 INDUCTION SYSTEM FOR ATWO-CYCLE ENGINE OF THREE CYLINDERS ElmerC. Kiekhaefer, Ccdarburg. Wis.Application May 24, 1951, Serla'lNo. 228,065

This invention relates to engines having three cylinders firingconsecutively and particularly Claims. (01. 123-.--'7:3)

to two-cycle engines employing crankcase induction and precompressionfor scavenging and recharging of the respective cylinders.

The invention provides two carburetors which are subject to individualadjustment and two separate induction systems associated therewith whichsupply jointly the intermediate crankcase with carbureted fuel and airand the respective adjacent crankcases individually with carbureted fueland air.

The principal object of the invention is to supply equal amounts ofcarbureted fuel and air in equal proportions at all times to the threecrankcases and cylinders.

A more particular object is to eliminate extensive manifold systemswhich cannot be arranged to deliver equal quantities of fuel at allspeeds from one or more carburetors connected thereto.

A further object is to provide for the adjustment of the carburetion asrequired for efficient three-cylinder engine operation and maximumoutput.

A more particular object is to eliminate individual carburetoradjustment for each respective cylinder in an engine of three cylindersor more and to eliminate a corresponding number of adjustments.

A further object is to make the engine operation noticeably responsiveto the adjustment of each carburetor employed without a common manifoldsystem.

These and other .object s and advantages will be more fully set forth inthe following description of a preferred embodiment of the invention asillustrated in the accompanyin drawing.

In the drawing:

Figure 1 is a side view of the engine with parts thereof broken away andsectioned generally in the vertical longitudinal plane of the cylinderaxes; and,

Fig. 2 is across-section of the engine taken on line 2-2 of Figure 1.

The engine shown in the drawing includes the cylinder block I and thecrankcase member 2, which latter is joined to one end of the block toenclose and support the crankshaft 3 in the upper and lower bearings 4and 5, respectively.

Crankshaft 3 includes the three crank throws 6 spaced 120 about thecrankshaft axis, and the bearings 1 intermediate the crank throws, whichseparate the crank throws axially of the crankshaft.

The semi-cylindrical bearing blocks 8 and 9.

assembled on bearings 1, engage and fit the corresponding complementalinner dimensions of member 2 and block I, to define therewith the threeindividual crank chambers H), H and i2 for the crank throws 6. Thecomplementary blocks 8 separate the upper and intermediate chambers 10and l l, respectively, and the similar blocks 9 separate theintermediate and lower chambers II and [2, respectively.

Each of the three cylinders l3 formed in block I is closed at its upperend by the block and opens downwardly into a corresponding crankchamber. A piston r4 carried in each cylinder l3 for reciprocation isconnected by a rod l5 with the corresponding crank throw 6.

The intake ports l6 opening into one side of each cylinder [3communicate with the corresponding crank chambers through the respectivetransfer passages H formed in block I. The exhaust ports l8 open fromthe opposite side of the cylinder into means, not shown, for dischargeof the exhaust from the engine.

Ports l6 and i3 are controlled by movement of pistons I4 covering anduncovering the ports to open and close the same. During the upwardstroke of the piston in each cylinder, the respective ports are closed,and the fuel charge in the upper combustion end of the cylinder iscompressed. At the same time, the induction of the succeeding fuelcharge into the crank chamber below the piston is effected, as will bedescribed. After cylinder firing, the downward power stroke continuesuntil the piston uncovers and opens ports IB, which provide for theexhaust of the burned gases, and shortly thereafter opens ports I6 fortransfer of the compressed fuel charge from the crank chamber to thecylinder through a passage I],

The complementary upper and lower crankcase bearing blocks Band 9 aresecured by screws is on the corresponding bearing! of crankshaft 3 andare provided respectively with passages 20 and 2|. Passages 20 and 2|register respectively with upper and lower openings 22 and 23 in member2, and open into the crank chambers through ports 24 formed in theblocks. Passages 20 open into chambers i0 and H, and passages Zl openinto chambers ll and 12.

The reeds 25 seated on blocks 8 and 9 normally cover and close thecorresponding ports 24 of each block. Each reed 25 is secured at one endto the corresponding block and is otherwise subject to flexing to openand close-the respective port in response to cyclic pressure changeseffected within the chamber by movement of the respective piston.

The construction of blocks 8 and 9 and the reed valves formed by ports24 and reeds 25 is similar to that described and claimed in thecopending application of the present inventor for Crankcase InductionValve for Two-Cycle Engine, Serial No. 117,325, filed September 23,1949. I

Each carburetor 28 and 21 includes a mixing passage 28 which is open atone end to receive the air.

The nozzles 29 of carburetors 26 and 21 are connected to a suitable,constant fuel supply by the fuel conduit 33, shown only in part. Eachcarburetor 26 and 27 includes a valve 3!, which provides for theadjustment of the fuel supply to the respective nozzle for a givenoperation condition of the engine and carburetor, and an adjustmentlever or stem 32 which may be turned,

while the engine is operating, to regulate the corresponding valve andthe mixture of carbureted fuel and air as desired and required for themost eihcient operation or greatest power output of the engine.

Carburetors 26 and 2? are carried by and secured to crankcase member 2with the passages 28 in communication respectively with the upper andlower openings 22 and 23 for the delivery of carbureted fuel and airmixture to chambers 19, H and i2.

Passages 20, communicating with the upper opening 22, provide for thedelivery of the fuel mixture from carburetor 26 through ports 2 tochambers ill and H, in response to the upward induction stroke of thecorresponding pistons l4, as described. Passages 2i, communicating withopening 23, provide for the delivery of the fuel mixture from carburetor2! through ports 25 to chambers H and I2, similarly in response to theupward induction stroke of the corresponding pistons.

According to the invention, each carburetor 2E and 2'! is disposed forthe delivery of fuel mixture to two of the three cylinders 43, so thatengine operation may be controlled by an adjustment of each ofcarburetors 26 and 21, first independently of and irrespective of theadjustment of the other, and thereafter reset as the adjustment requiredis indicated.

Optimum engine operation is approached by the adjustment of the twocarburetors made first independently of the other and with the latter ineach case deliberately set out of adjustment. With engine operation thendependent upon the first carburetor, the adjustment of the firstcarburetor may be made according to the response of the engine to suchadjustment. When maximum output of the engine is reached, the indicatedadjustment of the first carburetor is noted for later resetting, and thecarburetor is then set out of adjustment. The adjustment of the othercarburetor is then made as with the first carburetor, and thereafterboth carburetors may be reset to the indicated adjustment required forthe maximum output of the engine operating on both carburetors.

In engines provided with independent lubricating systems, not shown,each carburetor may be alternately adjusted with the other entirelyclosed to the delivery of fuel. In the engine shown and described whichis adapted to be operated with the lubrication provided with and by thefuel, the adjustment of each carburetor is preferably made with theother carburetor providing the delivery of air with sumcient fuel forlubrication purposes with or without some combustion. If desired, suchother carburetor may otherwise also be set to deliver an overrichmixture with a fuel-air ratio above the limits of optimum combustion,thus providing and adequately assuring the lubrication required.

The invention provides for the delivery of the fuel and air mixture tothree cylinders or crankcases arranged in line in the precise amountsnecessary for optimum engine operation.

In each instance, the engine is responsive directly to the carburetorbeing adjusted, and such adjustment may be made according to suchresponse.

The elimination of extensive manifold systems extending beyond .a givencylinder or crankcase is provided by limiting the induction systems tothe two'pair of adjacent cylinders. The coordinated adjustment of thecarburetors is made possible by the separate induction systems which areindependently adequate for engine operation. The adjustment of eachrespective carburetor independently of the other with the engine runningallows their adjustment by observation of engine operation and response.After both carburetors have been separately adjusted, as described, theymay be put in operation together for normal engine running with the fullassurance that both carburetors are delivering the proper fuel charge toeach of the three cylinders.

Various embodiments of the invention may be employed within the scope ofthe following claims.

I claim:

1. In an engine having three cylinders arranged in line and havingconsecutive induction cycles, two independently operable inductionsystems including separate, individual passages for delivery ofcarbureted fuel and air collectively to the intermediate cylinder andrespectively to each of the other two thereof, and valve meanscontrolling said passages and the induction of the fuel and air mixtureincluding valve means associated with said intermediate cylinderseparately controlling the passages of said independently operableinduction systems.

2. In an engine having three cylinders arranged in line and havingconsecutive induction cycles, two separate carbureting means for thedelivery of fuel and air mixture to the engine, said carbureting meansbeing capable of individual adjustment, and two independent inductionsystems for delivery of the fuel and air mixture from the respectivecarbureting means collectively to the intermediate cylinder andrespectively to the other two thereof wherein two of said threecylinders are subject and responsive to the adjustment of either of saidcarburetors.

3. In a two-cycle engine of the class described, a crankshaft havingthree crank throws spaced axially thereof and of each other about therotational axis thereof, a cylinder block having three cylindersarranged in line and respectively in operative relation to thecorresponding crank throws, a piston carried for reciprocation in eachcylinder and connected to the corresponding crank throw, a crankcasesupporting said crankshaft and including chambers separately enclosingeach crank throw, each of said cylinders opening into the correspondingchamber below the respective piston and having intake ports above andcontrolled by the piston and in communication with said correspondingchamber, in.

dividual passages opening into adjacent crank chambers, separatecarbureting devices for the delivery of carbureted fuel and air to thecorresponding individual passages, valve means controlling said passagesand the delivery or" carbureted fuel and air therefrom to the corrsponding crank chambers in timed relation to the reciprocation of saidpistons, and valve means for individually adjusting said carburetingdevices whereby the individual adjustment of the delivery of carburetedfuel and air to two crankcases and cylinders of the engine is providedby each of said valve means.

4. In a two-cycle engine of the class described, a crankshaft havingthree crank throws spaced axially thereof and 120 of each other aboutthe rotational axis thereof, a cylinder block having three cylindersarranged in line and respectively in operative relation to thecorresponding crank throws, a piston carried for reciprocation in eachcylinder and connected tothe corresponding crank throw, a crankcasesupporting said crank" shaft and including chambers separately enclosingeach crank throw, each of said cylinders opening into the correspondingchamber below the respective piston and having intake ports above andcontrolled by the piston and in communication with said correspondingchamber, individual passages opening into adjacent crank chambers,separate carbureting devices for the delivery of carbureted fuel and airto the corresponding individual passages, and valve means controllingsaid passages and the delivery of carbureted. fuel and air therefrom tothe corresponding crank chambers in timed relation to the reciprocationof said pistons and including means associated with the intermediatecrank chamber and separately controlling said passages thereto.

5. In a two-cycle engine of the class described, a crankshaft havingthree crank throws spaced axially thereof and 1 0 of each other aboutthe rotational axis thereof, a cylinder block having three cylindersarranged in line and respectively in operative relation to thecorresponding crank throws, a piston carried for reciprocation in eachcylinder and connected to the corresponding crank throw, a crankcasesupporting said crankshaft and including chambers separately enclosingeach crank throw, each of said cylinders opening into the correspondingchamber below the respective piston and having intake ports above andcontrolled by the piston and in communication with said correspondingchamber, individual passages opening into adjacent crank chambers,separate carbureting devices disposed to deliver carbureted fuel and airto the corresponding individual passages, valve means for adjusting saidcarbureting devices whereby the independent adjustment of the deliveryof carbureted fuel and air to two crankcases and cylinders of the engineis provided by each of said valve means, and corresponding valve meanscontrolling said individual passages and the delivery of carbureted fueland air therefrom to the corresponding crank chambers in timed relationto the reciprocation of said pistons whereby tWo of the three cylindersof the engine are subject and responsive to the adjustment of one ofsaid carbureting devices.

ELMER C. KIEKI-IAEFER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,050,456 Helin Jan. 14, 19131,318,542 Chevrolet Oct. 14, 1919 1,746,548 Meyer Feb. 11, 19302,254,365 Conover Dec. 2, 1941 2,282,458 Conover May 12, 1942

